Radiotelegraphy superregenerative receiver



' Oct'. 12, 1948. e. PETERSON 7 2,450,913

RADIO TELEGRAPHY SUPERREGENERATIVE RECEIVER Filed April 4, 1945 SUPER |OOQ N R-FAMP REGEN.

DET FILTER I EXMITTER LOCAL AUDIO R-FOSC. AMP.

x A v 5 8 RECORDER Monosc,

INVENTOR. GLEN PETERSON BY WMQ/fie/Q ATTORNEY Patented Oct. 12 I948 RADIOTELEGRAPHY SUPERREGENERATIV E RECEIVER Glen Peterson, Asbury Park, N. J.

- Application April 4, 1945, Serial No. 586,614

(Granted under the act of March 3, 1883, as

6 Claims.

v The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

' My invention relates generally to a radio signaling apparatus and method. More particularly,

it relates to a radio system in which a transmit ter normally transmits a continuous wave, Said wave is then interrupted in'accordance with a signal to be transmitted.

It is a principal object of my invention to provide improved and reliable means for receiving and translating signals of this type.

Prior systems of this type used a receiver incorporating a superregenerative detector to which was coupled a recorder or other type of repro ducer which was responsive to the noise currents normally present in such detector output in the noise reappears in the detector output and operates the recorder. However, noise is of I such varied amplitude and frequency content that operation of the recorder occasionally becomes erratic.

In accordance with this invention a locally generated carrier modulated at audio frequency is applied to the detector. A filter responsive to said audio frequency is inserted between the detector and the recorder. This local carrier is made weaker than the incoming carrier but stronger than the locally generated noise currents which are present, so that when the received carrier is present it swamps the local carrier and no audio modulation appears in the detector output so that the recorder does not operate. When the incoming carrier is interrupted, the local carrier swamps the noise currents and takes control of the detector so that the audio frequency modulation appears in the detector output and passes through the filter to the recorder.

For a better understanding of the invention, together with other and further objects thereof, reference is had to the following description taken in connection with the single figure in the accompanying drawing, which shows a block diagram of the invention.

The invention comprises a radio transmitter A amended April 30, 1928; 370 0. G. 757) and a receiver B. Transmitter A generates a continuous carrier wave under the control of a keyer 2 which is normally closed so that said wave is continuously being radiated by the antenna coupled to the output of the transmitter. To transmit a signal, keyer 2 is operated to inter mittently open its circuit and interrupt the generation of the carrier wave in accordance with the signal.

The receiver B comprises an antenna coupled to an R.-F. amplifier 3, the output of which may be converted to a lower frequency in accordance with the well-known superheterodyne principle, and then applied to the input circuit of a superregenerative detector 4. .Also applied to said input circuit of the detector is the output of a local oscillator 5 tuned to substantially the same frequency as the incoming carrier or to said converted frequency. Oscillator 4 is in turn amplitude modulated by the 1000 cycle output of an audio frequency oscillator 6.

The output amplitude of local oscillator 5 is so adjusted that it is greater than the amplitude of noise currents present, but less than the maximum amplitude, of the received carrier input to detector 4. Hence, when the incoming carrier is 7 present, that is, when keyer 2 does not interrupt the carrier transmission, the limiting action of detector 4 permits the latter to swamp both the local carrier output of oscillator 5 and the noise currents, whereby no 1000 cycle current appears in the output of detector 4, and the recorder 9 does not operate. When the received carrier is interrupted in accordance with a signal modulation, the signal from local oscillator 5 takes control during the interruptions, and an interrupted i000 cycle signal, modulated in accordance with the received carrier interruptions, appears in the output of detector 4, passes through the filter 1, and operates the recorder.

In place of the superregenerative type of limiting detector, it is to be understood that other wellknown types of limiters may be used.

While there has been described what is at present considered a preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. The method of translating continuous carrier wave having an amplitude which varies from an upper to a lower limit in accordance with a. de-

sired intelligence signal, which comprises the steps of locally generating a second continuous wave having substantially the same frequency as said carrier wave and an amplitude which is intermediate said upper and lower limits, modulating said second wave with a wave of substantially lower frequency, applying said first and second waves to a limiting type of detector which will not translate the modulation of said second wave when said carrier wave is at its upper amplitude limit, and filtering from the'output of said detector only currents of said lower frequency.

2. The method of translating continuous carrier waves which are interrupted in accordance with an intelligence signal, comprising the steps of locally generating a second continuous wave having substantially the same frequency as said carrier wave and an amplitude which is'less than the normal amplitude of said first wavebut greater than noise currents present, modulating said second wave with a lower frequency, superregeneratively detecting said first and second waves,

filtering from the output of said detector only cur- '-rents of said lower frequency, and reproducing .said'filtered output.

3. A translating system for a carrier wave whose normal amplitude is reduced in accordance with anintelligence signal, comprising an amplitudelimiting detector to which said carrier wave is said oscillator at an audio frequency rate, a filter coupled to the output of said detector and tuned to said audio frequency, and a, reproducer energized by the output of said filter, the amplitude -of said localoscillator being such that it is less than thenormal amplitude of said carrier wave, but greater than the reduced amplitude thereof,

and said detector being so constructed that it will 1 not respond to the modulations of said oscillator in'the presence of said carrier wave.

4, A translating system for a carrier wave which 'is interrupted in accordance with an intelligence signal comprising a superregenerative detector energized by said waves, a local oscillator -coupled to said detector, said oscillator being tuned to the frequency of said carrier wave,

means to modulate said oscillator at an audio frequency rate, a filter coupled to the output of 4 said detector and tuned to said audio frequency, and a signal reproduced energized by the output of said filter, the amplitude of said local oscillator being such that it is less than the normal amplitudeof said carrier wave, but greater than the amplitude of noise currents.

5. A normally operating radio system comprising a radio transmitter of continuous waves, means to reduce the amplitude of said waves in accordance with an intelligence signal, and a receiver for said waves comprising a limiting detector for said wave, a local oscillator tuned to the frequency of said waves, means to modulate said oscillator at a lower frequency, said oscillator being coupled to said detector, a filter coupled to the output of said detector and tuned to said lower frequency, and a signal reproducer energized by the output of said filter, the amplitude of said localoscillator being such that it is normally less than the maximum amplitude of the incoming waves but greater than said reduced amplitude.

cordance with an intelligence signal, and a receiver for said waves comprising an antenna, a carrierwave amplifier fed by said antenna, a superregenerative detector fed by the output of said amplifier, a local oscillator tuned to the frequency of said carrier waves, means-to modulate said oscillator at an audio frequency rate, said oscillator "being coupled to an input circuit of said detector,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED :STATES PATENTS Number Name Date 1,971,347 Hyland Aug. 28, 1934 1,999,247 Marrec et al Apr. 30, 1935 2,127,525 Marshall Aug. 23, 1938 2,131,109 Lowell Sept. 27, 1938 Certificate of Correction Patent No. 2,450,913. October 12, 1948. GLEN PETERSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 2, claim 4, for the word reproduced read reproducer;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of April, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommissz'oncr of Patents. 

